How do I apply sharpening via compositing to several movie clips simultaneously in my video editing project?
Afaik, there is no sharpening filter in Blender.
In general, if you need to add an effect filter to several strips, add an Adjustment Layer over all strips and add an effect to that.
For modifiers, there is a button in the sidebar/Strip Menu to copy the modifiers from the active strip to all selected strips.